Hey Pedro!!! I took your advice and decided to return.. I agree with your posting on harsher crits.. people won't learn as much otherwise.. at the very least we can agree to be 100% honest with each other..
okay! First, It's important for me to know what you want to do in art so that I can give advice accordingly. I mean, if you want to JUST focus on lineart of people it wouldn't be very helpful for me to suggest doing oil paintings in the forest..
For now I'll assume you that you want to be a realistic painter.. disregarding subject matter, you just want to be able to convey form and space in a believable way.
It a realistic painting lines would serve as the scaffolding on which you can place your shapes over (if you even place lines down at all). After everything about the shapes work.. (communication objects clearly, a working value scheme reflecting the mood of your piece, colour scheme, shape design, etc) then you could go about adding gradations softening edges. Anytime you have a shape where ALL of it's edges are the same, it will immediately feel flat. This isn't good or bad, it will just tell the viewer: THIS IS FLAT. I personally like pieces where areas of interest are modeled to show a convincing illusion of 3d, and certain background shapes are left flat. Another important thing is that if any shape is left as a single value will appear flat. That is, a shape without any (so many how subtle) value change inside will be flat. download/file.php?id=969
in that painting, you were able to lay down the shapes of the important planes, but then you made sure to gradate so that the final appearance was something with an illusion of 3D. If you look at the inside corner of her left (viewer right) eyebrow, you'll see that that end part is all the same value and each edge is hard. This is flat. Again, that's not good or bad, but I think It's important for artists to know what makes something look flat and what makes something look 3D. download/file.php?id=47601
This one is cool because you've figured out the important planes on the main guy to act as a solid foundation IF you wanted to make him look 3D. If it's a thumbnail or sketch, maybe that isn't your goal. Having clear designed (shape and value) shapes will make "rendering" them way easier. As it stands, I'd have to back up from my monitor a couple of feet and squint heavily in order for him to look convincingly 3D. It looks more like a sketch so I assume that making something look 3D wasn't part of the plan.
I get now why the masters of the past studied so intensely from life. All of the lessons are contained within a cast drawing.. assuming you have a teacher or someone to point out the whats and whys... otherwise it's just copying light and dark shapes. If your goal is to learn how to make things appear very realistic (like linran, for example: http://1.bp.blogspot.com/-4mQqWmc1K8E/U ... ion+02.jpg
) then i'd make sure to focus on long, intensive studies where you leave nothing unexplained. Doing cast drawings are ideal because of the controlled lighting and the fact that you are drawing from something IN 3 dimensions.. if you can't set that up, then id find pictures of greek or roman sculpture with decent lighting and study the SHIT out of those. Don't stop until you've created an exact replica.. but make sure that just making a replica of a picture is the goal.. you want to learn every that you can from that picture (or cast).
So the most important thing is for you to know exactly where you want to go with your art. The clearer your vision, the clearer the solution!